Lazy eye, or amblyopia is a condition, where in most cases one eye does not see with the same visual acuity as the other eye, and poorly transmits visual information to the brain. If you cover the healthy eye, people with amblyopia will have a difficult time making out things, or may see very little at all. Sometimes cases are very minor and aren’t significantly noticed without performing a test where one eye is covered. The healthy eye may compensate for the lazy one, and cause very few changes to actual vision. In more severe case, depth perception is significantly affected.
There are three main types of lazy eye: strabismic, refractive or anisometropic, and form deprivation and occlusion. Strabismus is not amblyopia, but amblyopia may be caused by an eye that is strabismic, having a different focus point from the healthy eye. The eye without strabismus tends to take over and be dominant. Treatment of strabismus of any type is important so that both eyes are able to transmit visual images accurately.
If you have refractive lazy eye, your eyes send images to your brain at different speeds. The faster eye creates a much more accurate picture and begins to be favored. This form is corrected by glasses, and sometimes by using an eye patch over the dominant eye to help the mind readjust to relying on both eyes for sight.
If a single eye forms cataracts or has been injured to the point where seeing is affected, sometimes occurring in forceps delivery of infants, this is called form-deprivation or occlusion amblyopia. When possible, injury to the eye or cataracts are cleared to avoid permanent obstruction of vision in the affected lazy eye.
When the condition occurs in childhood, which is most common except for the development of cataracts or sustained eye injury, emphasis is on correcting any conditions creating poor eyesight, using glasses, visual exercises, and blocking the dominant eye. Lazy eye is best treated as soon as possible, with children under 5 usually having the best results for complete correction. Treatment later in life can be much more complicated since the condition is a brain disorder rather than a muscular one. Long dependence on a dominant eye creates greater difficulty in addressing the problem.
Still, many children who are treated after the age of 5 have a good chance of improving their vision. Even if vision is not completely normal, treatment will result in better vision than if treatment is not sought.